A sticker saying "Beware propaganda, 80% of UK news outlets are owned by 5 billionaires who serve vested interests (& the BBC has right wing bias). The current system is failing, Alternatives exist that share resources fairly and protect life on earth."
It is 60mm x 60mm and can be printed 12 to a sheet by a local printer. A legal advisor suggested attaching to free newspapers should be OK since they don't belong to anyone.